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JavaScript Storage Events — exercises and bug fixes

5 hands-on exercises and 5 find-the-bug challenges for the JavaScript Storage Events lesson. Every one is checked automatically in the browser — write the code, run it, and the tests tell you what still fails.

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Exercises(5)

  1. 1

    See it does not fire locally

    easy10 min

    Show that changing storage in the same tab does not fire the event.

  2. 2

    Read the event details

    easy10 min

    Build a message from a fake storage event.

  3. 3

    React to one key

    easy10 min

    Only respond when the logout key changes.

  4. 4

    Detect a full clear

    easy10 min

    Report a full clear when the key is null.

  5. 5

    Attach and check the listener type

    medium10 min

    Confirm a storage listener was actually attached.

Find the bug(5)

  1. 1

    Fix the event expected in the same tab

    easy8 min

    The storage event never fires in the tab making the change.

  2. 2

    Fix the wrong key checked

    easy8 min

    The handler is looking at the wrong property name.

  3. 3

    Fix the clear check using undefined

    easy8 min

    A full clear sets key to null, not undefined.

  4. 4

    Fix the listener attached to storage itself

    easy8 min

    The event is listened for on window, not on localStorage.

  5. 5

    Fix the message built with the wrong order

    easy8 min

    The old value should come before the new one.

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